Repeatered electrical transmission system, including auxiliary cable system



prll 18, 1950 Q B, JACOBS 2,504,692

REPEATERED ELECTRICAL TRANSMISSION SYSTEM, INCLUDING AUXILIARY CABLE SYSTEM Filed July 3l, 1946 4 Sheets-sheet l SIGNAL/.ma Alva/on Recs/wma c/Rcu/Ts REFEA TERS ATTOP V B.' JACOBS REPEATERED ELECTRICAL TRANSMISSION SYSTEM,

April 18, 1950 O.

INCLUDING AUXILIARY CABLE SYSTEM 4 Sheets-Sheet 2 Filed July 3l, 1946 ATTORNEY 4 Sheets-Sheet 5 /NVE/VTOR OBJCOBS BV ATTORNEY BI JACOBS O. REPEATERED ELECTRICAL TRANSMISSION SYSTEM, INCLUDING AUXILIARY CABLE SYSTEM April 18, 1950 Filed July 31, 1946 April 18, 1950 o. B. JACOBS REPEATERED ELECTRICAL TRANSMISSION SYSTEM,

INCLUDING AUXILIARY CABLE SYSTEM 4 Sheets-Sheet 4 Filed July 51, 1946 Patented Apr. 18, 19510 REPEATERED ELECTRICAL TRANSMISSION SYSTEM, INCLUDING AUXILIARY. CABLE SYSTEM Oliver B. Jacobs, Morristown, N. J., assgnor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application July 31, 1946, Serial No. 687,428

17 Claims. (Cl. 179-170) tions has heretofore been considered impractica ble under conditions where the hazard of cable damage and prolonged interruptions to service are great.

The problem therefore arises in a long repeatered system of. supplying direct-current power to the repeaters over the cable without the use of potentials high enough to impair the service life or transmission performance of the system. Certain condensers in the repeaters nearest the shore stations are the elementschiefiy concerned, since these are subjected to nearly the total potential of the power source, and their service life varies inversely as approximately the fifth power of the applied voltage. Other factors which make it desirable to restrict the applied potential are (1) possible weak spots in the cable insulation; (2) limited clearances between re'- peater wiring and the container; and (3) noise caused by corona discharges.

Moreover, the problem also arises of providing in such a system, continuous service in regions where damage may be caused by icebergs or by trawling operations, or where ice conditions would prevent the carrying out of repairs during portions of each year.

It is therefore a broad object of this invention to minimize the duration of interruptions to service resulting from faults in electrical transmission systems.

A more specic object of this invention is to enable the use of lower terminal voltages in the energizing circuits of extended repeatered submarine cable systems.

It is contemplated that the various features of this invention will be useful in electrical transmission systems of many'diffe'rent types; however, for the purposes of illustration, the invention is described herein as adapted to a repeatered submarine cable system.

In accordance with this invention, a main deep sea cable is connected to any one of two or `more l 2 Y alternative branch cables extending through hazardous areas to a respective land station, by remote control. The invention contemplates the use of a system of relays at the connecting junction between main and branch cables which is s0 arranged that the proper connections are automatically made at such point whenever power for energizing the system is applied to or removed from any one of the branch cables.

f A further feature of the invention includes means for normally supplying power for energizing repeaters at a point intermediate of the terminals of a main cable by way of a branch cable or alternative branch cables extending to one or-j more land based power supplies, without routing the main cable signal currentsy through the power supply station. In such a system remotely controlled connectionspermit either (1) normal operation using both the intermediate and terminal power supplies, or (2) koperation wherebyv the system is energized entirely from the main cable terminal stations in case the branchcableor cables are faulty. v

In accordance with certain specic embodiments of the invention, which are described later in detail, the interconnecting system comprises one or more relays disposed in a water-tight container located at the junction of a main cable with one or more power feeder cables or withtwo or more shore end cables, the relays being so connected that the application of power to any one of the alternative cables from the associated shore station will cause that cable to be connected to the main cable, and all other connections to be simultaneously locked out.' In each case, the controlling relay has its winding in the path of the energizing current and remains operated as long as that current continues.

In case of a system employing a power feeder cable, the energizing current flows in opposite directions from the'junction point in the main cable, and the polarity of the voltage applied to the feeder cable at the shore vstation is opposite tothat applied to both of the terminal stations of the main cable. In the event that the power feeder cable becomes faulty and no alternative feeder cable has been provided, the cable system can be operated by means ofincreased potentials at the terminal stations which, though not cori-v sidered satisfactory for permanent operation, would supply a reduced amount of energizing current sufficient to give a passable gradefof service.

Such type of operation is possible under two alter-g native conditions (l) if the repeaters betweenonej of the terminals and the feeder junction pointl are equipped to operate with current flowing in either direction, Vor (2) ifthe relay circuits provide a. solid ground connection when not operated. In the latter case the invention provides for the groundirigofgtliefniain gable.

otherr beers endif? features of Imis; invention will be apparent from a study of the specification Y and the attached drawings, of which:

Fig. V1A shows a repeater ,Clllit ,comprising` "ai` 511er rection rectifying bridge to enable o plied with energizing curretv'i along the cable.

Fig. 1B shows a submarine cable; ,system in:

,01.1 leither cluding repeaters, which system4 compr-15gg @im in, cable having terminal power sources. andan ahv t iliary power source and associated auxiliary cable l Y a i s et; ferie? mth, repeaters used in 'such cases include the rectifying 'nc'ti'on'l between 'main'and f between s @energize therepeat S. H

Sterre it; Teach)v 6t- Y w bridge circuit shown in Fig. 1A. Referring to Fig. 1A, energizing current flowing in a W-E direction along the cable core flows into the repeater circuit through the inductance a, where it divides,

iloyv'ing'intothe repeater cathode heater circuitsthrolighy the branch band into the' inductance f, and part flowing into the plate circuits through the one-way Valve c, from which it flows throughthe ,respective tubes Vto the cathode cirrth, o'ne-way'valve e, and into the eastern cab;` 'si @tion through the inductance f. Current flowing in an E-W direction along the cablecoreilows .into the repeater circuit through the'inductanee f, where it divides, part owing into the heater circuit through branch h and into the inducta'ncemvand part flowing through the oieway valve- Vginto the plate circuits to the re- V'tre cathode circuits, and through the onealv d into the western cable half through the inductance a. By means of Vthis circuit, the repeater l 'plates are alwaysinaintined at. a 'positi'w 'p'oi'ier'itialr with respect to the cathodes", re' gadlessbf the'f direction oli-current new inthe cable. Current flow in the heater circuits may ther directon. cc

, n es 1g @ma tV an intere ...les f Whib elgoee'ctedt ilbh' tiene@ the festeggia tendensen i4. 'ad d "elstors fat-ige ree-petti@ @atie tgv Thil-12:15. v u A Y *Y n l et. 'the terminal stati@ Ar diret @11j-rentrer@ e. Source; t5; or; the nggat, bleh; maxe torv eamplei surgir:` roltagesloffthe Order ory 2,009 volts posi: tive or negative ,in accordance w'th whetherfthe; Seite@ l@ is ponteggi @legata VSE-heath@ switch l@ is Connected te. Heuer ,from thetermnalzstatgn A-i-s.l c oA4 pletely. The switch I8 is connected through g, lilielilleieirtuit lfftofthelnrier,gedient@ C. l@ lmialff by.Y the primeramen- 23 is connected through its a or b contact to the terminal of the auxiliary cable 24. The cable 24 is connected 'to the relay R and is preferably of similarconstruction to the main cable described hereinbefore.

If the junction J lies intermediate of the repeaters |I, as shown in Fig. 1B, it is preferably joined to the relay circuit R at contact point 28 through the inductance 29, which is designed to have a reactance of approximately 2,500 ohms at the lowest-transmitted frequency in order to prevent material transmission loss from the main cable. A condenser-to-ground 21, having a capacitance of the order of one-half of a microfarad, provides a shunt-to-ground to prevent noise from the auxiliary power supply from interfering with the transmitted signals on the main cable. If the junction J lies at either end of the heater circuit in-one of the repeaters I I, the condenser 2'| may be omitted, and the inductance 29 need be only large enough to prevent too great a surge of current in case of a sudden fault on the cable 24.

The relay R comprising the operating winding 25 is a conventional neutral relay which is designed to operate in response to current strength considerably below that normally carried in the auxiliary power cable 24. Associated with the relay R are the left-hand make-before-break contactsv 25a and 25h, and the symmetrically placedright-hand contacts 25c and 25d. When the relay winding 25 is deenergized, a current path is provided through the break-contact 25h to ground 26; similarly, the ground I2 is connected to the junction 28 through the break contact 25d. The contacts |2 and 26 are sea grounds, which ordinarily comprise short-circuit connections to the outer cable armor.

As long as the relay 25 remains deenergized, the ground I2 is connected to the junction 28, s'o that the energizing circuit for those repeaters II disposed on the western half of the cable extends from the station A to the junction J, and for the repeaters I I on the eastern half, from station B to the junction J.

When power of the opposite polarity to that applied at the terminal stations A and B is applied from one of the direct current sources 2 Iv or 22 of station C, the relay winding 25 is energized operating the right-hand break contact 25d to release the ground I2. The make-before-break combination 25a-.25b is also operated to disconnect the ground 26 and provide a path for direct current power to ow from one of the sources 2| or 22 at C, through the auxiliary cable 24, the relay winding 25, the junction 28, and the inductance 29 to the junction J, where the circuit divides, permitting current ow in both directions therefrom along the main cable to the stations Aand B.

Assume it is desired to utilize the auxiliary source at station C for energizing the repeaters |I. The operator at station C positions the switch on the contact 23a, first adjusting the associated rheostat, so that a positive voltage sufficient to supply a current of, for example 100 milliamperes, is impressed on the terminals of the cable 24. Simultaneously, the switches I8 andA I 8 at-the respective terminal stations A and B are positioned so that negative potentials equivalent to the aforesaid positive potentials are impressed on the cable terminals at A and B, which are assumed to be approximately equidistant from the junction J. The relay R then operates to make the desired connection.

For optimumY performance of the system, and? in order to prevent current surges, equal andopposite potentials should be gradually and simultaneously built up at the auxiliary station C and at the terminal stations A and B in the manner prescribed in my Patent 2,020,316, November 12, 1935.

When current from the auxiliary source C ceases to ow through the relay circuit R, either through action of the operator or through operational failure, the auxiliary cable 24 is automatically connected to ground 26, and the main cable is again connected to ground I2.

By application of substantially larger direct current potentials at each ofthe cable terminals A and B, thereby enabling current to low from the respective terminals to ground at J or vice versa, depending on the polarity, the repeaters I I may be energized, making the main cable operative while the auxiliary cable 24 is tested or` repaired. Y

If it is desired to avoid having the main cable grounded when it is not energized, the ground I2 may be omitted, and the cable energized by voltages of opposite polarity applied at the respective main terminals, provided that the repeaters are equipped to operate when supplied with energizing current in either direction. Without the last-named feature, the ground connection must be retained in order to energize the main cable solely from its terminals. Obviously, if the repeaters are operable under only one direction of current flow, a given terminal would be equipped with a power supply of only one polarity.

Fig. 2 shows a modification of the system of Fig. 1B in which the repeaters II of the main cable I0 are adapted to be alternatively energized by direct current power from one of two auxiliary stations, C and D, through operation of the relay circuit R' which is adapted to connect the rst energized one of the pair to the main cable through the junction J, and lock the other out of operation. Other parts of the system, namely, the terminal stations A and B, the cable |IJ and intervening repeaters Il, are as described with reference to Fig. 1. y

As hereinbefore described with reference to Fig. 1B, the auxiliary stations of Fig. 2 may each have both positive and negative sources of potental I2 I, |22, at station C, and 22 I, 222, at station D, which may be alternatively connected to the respective auxiliary cables |24 for C and 224 for D through the respective switches |23 and 223, which are similar to the switch 23 of Fig. 1B.

The auxiliary cable |24 from station C is connected to the energizing windings of the neutral relay |25, which is equipped with the left-hand make-before-break contacts I25a and I25b, and the right-hand break contact I 25d. Similarly, the 'auxiliary cable '224 from station D is connected tothe energizing windings of the neutral relay 225, which is equipped with the right-hand make-before-break vcontacts 22511 and 225D, and the left-hand break contact 2251i. When the relays |25 and 225 are both deenergized, the ground I|2 is connected to the windings of relay |25 through its break contacts |25d and |25b; and to the windings of the relay 225 through its break contact 225d and 225b.

Assume that a direct current positive potential is applied to the cable |24 at the auxiliary station C, which, if correspondingnegative potentials areapplied at the terminal ,stations` A and B, issuicient to supply a current of, forexample,

aimera;

` 125 their `operates vitsbrealeV contact I'25d releas-v ing the ground contact I I2 from the circuit of the Y relay 2.25,- and-4 thereby locking itltto voperation inthe event that a potential is. appliedrat stan tion D.; The vrelay: I 251` i also* operates: thergmake before-break combination.. I25a+ i255.; releasing,Y

K tliepgrouncl:v II2,.' and providingforzcurrent.new

from the stationzC, through thezenergizing. windings of relay: I 2551;()vv the' junction 28; andgthrough theinductanceto thejunctioriJ. with-theme11; cablre III,... 'Y Y if the now-.of current Gils! cutroif for seine reason, causingltherelayr titi Y to;bec`ome .deenergired,` and: powergis their applied from thestationD, the relay-2.25 acts iria similar manner to that described above to lock the aux:

Viliary source Cout of operation, and-connect the sourcevDato the' maincablethrough the induct` ance 29]. The inductance 29 and the; condenser 2l are similar in function and structure to those same'V numeraled elements.- described with -reference to Fig. 1B.-

Inl th'e eventthat .thevauxiliarysourceslC and Dare both disconnected, anditis desired` to ene ergize@ the cable Iso'lely from its terminalsfby applied potentialsof thesa'ine polarity, Va. ground similar. totheground'r I2 oi' Fig. l'B'can beprof vided which isadapted to bedisconnectedbyoperatiorirof either of the relays I25'or. 225;

Fig. 3Y shows arfurther modification of thecir.- cuit of Fig. .1B which includes, in addition to the relay circuit R which isresponsive to connectthe' auxiliary source C to energize the repeaters IIf, a delayed Vaction relay circuit DR which is'responfsive to direct current potentials of oppositepolare` ityV fromrthe terrninalsv A and B to ground. the main cable only whenrit is energized solely from the terminals.

. The terminal stations A and B, the main cable IIJ', the intervening repeaters I Ir, the' auxiliary lstation G, aridthe connecting cab1e1324 laresi-ibstantially the same as described Vwith reference to the previousrfigures. Y

The relay 325' is arconventional neutral relay, siinilar tothe'relay 25 ydescribed with` reference to -FigllB, and 'is equipped withthe left-handmakee before-'break contacts 325a and 325b,vthe rightf; fia-iid make-'before-break contacts'325e and 32ml,v tlie outer left-hand break contact 325e andthe outer right-handhreak Yczznntact,.32f-.z YAs shown .theg auxiliary station a Y eryiseuorilieeifrom; thestetieei tets @miv zijfremelww the'respecre relesrstkeuc.. .ar size .Wheapower ceases ,tefleuffrereil station C, the relay 325 deenergizes, contacts :to their-encrnalresitieua.' maireecontacts 9.135@` and. 32541;.; are., .rele @di thereby disconnecting the; mailt;

B.- Preferablm .small potentials 11o-opposite cableeterminalsand allyeridy simultaneouslyriutherma in .my Patent; 2,020,3;1,6.sotnet th @tende ground entitle-.junction Niekept.:

Assuming direct current voltage of av'posite polarity. tobeapplied atfstatiengA.. and cita. negative 'polarity at station, current theniowsi from the Westernsection of the, mairicable III.; throughv the inductance: 'is-2.9. `centaet 3256er; .the relay` 325, throuehthe energizing. vuit-` of the. relaytl, and the.y energiai-ng. circuit orgthe relay 32; from which it flows intotlie eastern section o the main cable w' through. te coutatff ofthe relay 325, and the inductancegz.

The relays si and. 3;2 .are conventional neutral: relays designed to operate in responsef110i.consi@ieri-VY ably` less current than normally carried: the cable ill.. y'IherelayriI isieqllppedqwith the left: handzbreak Contact ely-.and the righ handemelse contact 3m;V while the' relax: 32a is similarly. equipped" with the right-hand.; break 0011.1.'@9121331 and thelleft-hand malrecontaet 33z' i Y When thecurrent. flow in. the; circuit becomes sufficient, the relays fai and .32opera'te-r disengag-` ing their respective break contacts; f3Igv andga, breaking the. circuit. tolerar-1nd 31.3; .in .wie Places and eliminating the possibilityofgppwen ow. frgm the auxiliary station-C. Simultaneouslyfthemake contacts. 3 I h and 321ik are' engaged, whereby., rent mayzilow through theiwindingsrof the relatie,V

V Y .V3I and .32 respectiyelygthe.'resistancey andth the or'ipositeV polarity ther-etuis supplied `from the Y terminal stations'A Aand B, .the relay 32:5 operates its make-before-.break contacts 32511 and 32.5dso that power ows. in both directions Yfrom the windingsi ofthe relay 325 through the respective inductors :liza and 229 tothe western eastern halves of the cable I0. Aswexplained hereinbee fore,y if vtlie relay vcir-cuit R Aisl positioned .at a re-V patei"i the indu'ctors .129 Aand 22.9 are .substan-.i

windings oi thefrelay .35. torground 35,"it the potentials of the. respective: junctions .orgJf-i are above or' below. ground potential; VV'Ill'ie'x'elenl-A 3'0' is a conventional slow-.actingi nonfpolarized. type which Yis equipped with a; copper yoke. ganadas" signedV to operatejin responseftol a predetermined current strength passing through theewindingsio: a predetermined ,timeinterval As .soonascurrent is built up Vsufliciently. to operaterelays 3i 351x132, the applied potential aty station'A, fory example. would be removed. Then current from station B would flow through the Vwindings of relayy 35, which operates .to engageitsfmakeecontaet .3511; thereby shuntin'g out the4 resistance. which functions initially Ato minimize ground ourge which mightoccur in .case the main -.caline iis. not at ground potential. when the relaysV 31. operate An inductancemay.v also .be .included in the .groundfcircuitif desired. but should not l be 4arranged to. be shontfcircuited unless con? siderable resistanceis included it. {I'heproz vision .of means for reducing surgexmirrents is important, since .asudden iailure of the. power supply. from the. :auxiliary source CL fwith cotiser quent release of relay 25, might fin a surge from .one fof jgtlfxesimalf infiltre.

. awww other through the relays 3| and 32, thereby, estaban elevated potential.

After the relays 3| and 32 have operated and the potential applied at the station which reversed its normal polarity for the foregoing operation has been removed, it is built up again with the opposite polarity for the purpose of operating the repeaters I I for signal transmission. As long as one of the respective relays 3| or 32 remains operated by applied potential fromv either of the terminal stations A or B, the ground 36 remains connected to the main cable. The other relay, when again operated, closes a parallel connection to ground 36.

Fig. 4 of the drawing shows a submarine cable system similar to those previously described in which a relay system RX, disposed at a junction in the main cable I8 is adapted to connect thereto Whichever of the cables 4 I Il or 5 I D from the respective terminal stations E and F is iirst energized,

and to lock the unused cable out of operation.

The energizing and signaling circuits of terminal stations A are substantially as described with reference to the drawings hereinbefore. The alternative terminal stations E and F include both signaling and repeater energizing circuits which have beeny given designations, in the fourhoundreds for circuit elements associated with station E, and in the five-hundreds for circuit elements associated with station F, which correspond to the tens designations assigned to similar circuit elements hereinbefore described with reference to stations A and B. Thus, signaling circuits 4|5 and 5I5 may be assumed similar in function and construction to the signaling circuit I5, hereinbefore described, etc.

As in the cases of the previously described relay junctions, the junction JX may either be located between repeaters on the main cable, as shown in Fig. 4, or it may be located at a repeater, in which case the leads 43 and 44, instead of being connected together as shown, Aare respectively connected to the repeater output circuit and the repeater heater circuit. As stated with reference to previously described circuits, the inductance 629, which serves to minimize surge currents from the main cable to ground, may be substani tially reduced in value if the junction JX is located at a repeater; and the condenser 621 may be omitted altogether in such case. At the respective junctions Je and Jr the inductances 429 and 529 function in a similar manner to theinductance 629 to keep the alternating current telegraph and speech signals from being shunted by the relay circuits.

The relay system RX comprises the non-polar relays 31, 38, 45 and 4I. voltage break-down requirements on the contacts of relays 38 and 40, the system is preferably designed so that when cable l|| is energized, relays 48 and '4| are isolated therefrom and from ground; and conversely, when cable |[I is energized, relays 31 and 38 are isolated therefrom and from ground. The relays 31 and 4| are therefore designed to withstand high voltage across their open contacts in the operated condition, thus permitting relays 38 and 40 to be designed to operate at .a low enough voltage to avoid condition which would result in severe current surges when connections to the main cable are made. The relay 38, which is designed so that a considerable part of its windings arev shunted out after initial operation, .is equipped with the left-hand break contact 38e, outer and In order to reduce the Y inner left-hand make contactsb and 38a,y and right-hand make-before-break contacts 38d and 38e. The relay 40, which is in generalsimilar to the relay 38, is equipped with, the left-hand make contact 40a, and right-hand make-beforebreak contacts 4019 and 40e. The relay 31, which is normally shunted out by the contacts of relay 38, is equipped with the right-hand make con- I tact 31a, and the break contacts 31h, 31c and of the drawings assume their normal or unoperated positions. y q

If it is desired to connect branch cable 4||| to the main cable l0, assuming none of the cables is energized, the relay circuit RX operates in the following manner. Low voltagesk of opposite polarity are applied at the shore terminals A and E in the manner previously described; Current then ows through the inductance 429 to the energizing circuit of the relay 38 through the break contact 38e which normally short-circuits the relay 31and from the windings thereof to ground 42 through the break contact 31h under control of the relay 31 and the break contact 4Ic under control of the relay 4|. K

The relay 38 is then energized to perform the following operations. 1

The make contact` 38a is actuated toconnect the grounded kend of the windings, of relay 38 lto the junction JX through the inductance 629.

The make contact 38h is engaged, whereby the cable 4|0 is connected to the main cable In at the junction Jx.

The two foregoing operationsy respectively connect theenergizing and signaling circuits of the branch cable 4|0 to the main cable IIL'and maintain such connectionl as long as the cable 4I!! is energized.

After the above-,described operations are complete, the break contact 38e is actuate dthereby releasing the shunt across the relay 31, and causing it to become energized, to perform the following operations. `The break contact 31h operates to release ground 42 from the windings of the relay 38, and the make contact 31a is subsequently engaged, whereby the part of the windings unnecessary to maintain the relay in operation is shunted out. n 1

Simultaneously, the break contact 31e is operated to disconnect the circuit of relay 40 from ground 39; and the break contact l31d is," operated. The aforesaid operations isolate relays 40 and 4| from ground and from the cable 5I8, in order to reduce voltage break-down requirements, as pointed out herelnbefore. The relays 40 and 4|, which are responsive to energy from the cable 5|0, arev thus locked out of operation for as long a period as power is suppliedthrough branch cable 4|0. I Y i v If it is desired to use the branch cable 5l0 in- I stead of the cable 4|ll as described, a low voltage is applied at station F. Operation of the relays 40 and 4I is similar to the above-described op eration of relays 31 and 38, excepting that' the junction Jr with the cable 5I0 is normally connected to the junction Jx of the main cable I0 through the Ybreak contact 38e of thedeenergized relay 38. Correspondingly, relays 31 and 38 are locked out of operation.

It will be apparent from a study kof theabove circuits that the principles of this invention. can be applied to the design of circuits which would allow any oneV ofl more than twocables to be 13 said junction exclusively for the transmission of pwer current thereto, g

112. A submarine cable signaling system in accordance with claim 1,1 which includes a connection to ground at said junction, and in which the deenergization of said relay operates to apply said ground connection at said junction to the power transmissionficircuit of said two connected signal-transmitting cable sections.

13. A submarine cable signaling system in acerdance with claim. 12 which includes additional relay means disposed at said junction and operated by currentsga; of different polarities simultaneously applied at the terminals of said connected signal-transmitting cable sections to aI- plply said ground connection at said junction tothe power transmission circuit thereof.

14. A submarine cabledsignaling system in ac- "dance with claim 13 in which the relay means tn'fpply said ground connection at said junction of said connected signal-transmitting sections is maintained in operation ',by power current from either one of said terminals.

115. A submarine cablesignaling system in accord'ance with claim 9 inwhich said power current.v for energizing said repeaters is direct current. y

' ,16,- A submarine cable signaling system in accordance with claim 9 inwhich said means including an electromagnetic relay to control the connection of one ofsaidcable sections with anof said cable sections at said junction inc-,udes circuit means to*lock an unused cable section out of operation.

11j-175A submarine cable signaling system which comprises in combination at least three cable sections having a common undersea junction,

14 1 certain of said cable sections including signal repeaters connected in tandem relationship therealong and having their energizing circuits `connected in series through a section of said 'cable including said signal repeaters, at least three corresponding sources of power substantially removed from said junction for energizing said repeaters, atleast three corresponding signal translating; circuits substantially removed from said junction, each of said cable sections connected to receive power current from a res'pective one of said power sources and to re- .ceive signal currents from a respective one of said signal translating circuits, and means to .control the connection of one of said cable sections with another of said cable sections for the ,transmission of power current to energize said 'repeaters and for the transmission of signal currents, said means including an electromagnetic relay disposed at said junction and having an operating circuit connected to be energized .by the power current from one of said last- -named cable sections.

OLIVER B. JACOBS.

REFERENCES CITED The following references are of record in the iile of this patent:

Y UNITED STATES PATENTS Number l Name Date n 2,020,297 Buckley et al. Nov. 12, 1935 2,020,316 Jacobs Nov. 12, 1935 v 2,079,689 Gorton May 11, 1937 2,263,320 Trucksess Nov. 18, 1941 2,288,487 Rosen June 30, 1942 2,329,010

Spencer Sept. 7, 1943 

